Model mp150

Heart rate (HR) and skin conductance level (SCL) were collected using the BIOPAC 6-channel acquisition system (BIOPAC Systems Inc., Model MP150, Goleta, CA). A two-electrode configuration was used with a bioimpedance ground reference module to collect HR data, which was indexed as intervals between R-spikes. Mindware Technologies HRV 2.33 software [44 ] was used to process HR data, which allowed R-R intervals to be calculated. The identification of R-spikes in Mindware were visually inspected and cleaned for movement artifact and double-scored by study personnel. Participants’ mean HR was exported and analyzed across 30-s segments across the baseline and emotion inductions, and as one 10-s segment during the manipulation (i.e., validation or invalidation).

After trauma-related memory retrieval, the rats were observed with an infrared camera to determine whether they presented startled awakening; the EEG and EMG were monitored simultaneously. The recording sessions occurred between 10:00 AM and 4:00 PM.
For electrophysiological recording, a lightweight shielded cable was plugged into the connector on the rat’s head and attached to a counterbalanced swivel that permitted free movement. The signals were routed to an electroencephalograph (Model MP 150, BIOPAC Systems, Goleta, CA, USA). The signals were amplified and filtered (EEG, 0.5–30 Hz; EMG, 16–128 Hz), digitized at a sampling rate of 128 Hz, and recorded using AcqKnowledge software (BIOPAC Systems). The EEG/EMG recordings were analyzed using SleepSign 2.0 software52 (link).

EMG activity of the vastus lateralis and rectus femoris muscles was recorded at a sampling rate of 2 kHz and filtered (10–500 Hz) using Acq-Knowledge analysis software (Model MP150, Biopac System, Santa Barbara, CA) using pairs of pre-gelled Ag/AgCl surface electrodes (recording diameter of 10 mm; Mini KR, Controle Graphique S.A., Brie-Comte-Robert, France). The skin was shaved, abraded, and cleaned with isopropyl alcohol; then, electrodes were taped lengthwise over the middle of the muscle belly with an inter-electrode distance of 20 mm following the SENIAM recommendations (Hermens et al., 2000 (link)). The reference electrode was positioned on the contralateral patella. The root-mean square (RMS) value of the EMG was calculated for each muscle over a 100 ms period at the peak torque (i.e., 50 ms before and 50 ms after the peak) during the MVIC and normalized by the corresponding M-wave amplitude (RMS_MVIC/M). The RMS-EMG of the RF and VL muscles was also calculated over a 100 ms period before the transcranial magnetic stimulation (TMS) stimulus artifact and normalized to the RMS_MVIC to control muscle activity during MEP recordings (RMS_MEP/RMS_MVIC).

Behavioral seizure scoring and electrophysiological (EEG) evaluations were performed at the last PTZ administration. Two unipolar scalp electrodes were placed on the bilateral temporal skin of the mice. Then, the mice were allowed to move freely in transparent cages. The baseline EEG was recorded for approximately 15 min before the injection of PTZ or saline, and then the EEG was recorded for at least 30 min using the numerical acquisition system (BIOPAC System Inc., Goleta, CA, USA, Model MP150). An electrophysiological seizure was defined as a seizure with a high frequency (> 5 Hz) and high amplitude (> 2 times the baseline) that lasted for more than 5 s. The seizure intensity was assessed based on the Racine scale: stage 0, no response; stage 1, mouth and facial movements; stage 2, head nodding; stage 3, forelimb clonus; stage 4, rearing; stage 5, rearing and falling; stage 6, death [33 (link)]. The behavioral data captured by the synchronized video recording system were used to confirm EEG seizure activity.